Stiemer, Genk
Stiemer as a reborn blue-green landscape pearl in Genk
The Stiemer Valley is a green-blue vein that runs through the heart of Genk, Limburg. The Stiemerbeek that runs there is accompanied by two Aquafin collectors on both sides that drain wastewater, but due to an outdated system and heavier rainfall, the region had to contend with waste nuisance and odour nuisance. Aquafin has joined forces with the city of Genk and our People and Environment team to tackle the water problem. Goal? Improve the water quality of the Stiemerbeek and prevent surface water from flowing to the collectors.
What was the problem exactly? A sewer collector runs along both sides of the Stiemerbeek in which the wastewater from East and West Genk is collected to end up in the water treatment plant. The collector can be seen as the highway for wastewater. As soon as too much water accumulates in the pipe, you create traffic jams and excess water is evacuated via overflows to the nearest canal or watercourse such as the Stiemerbeek. However, heavy rainfall caused waste and rainwater in the collector, causing it to end up in the Stiemerbeek and the water quality to deteriorate.
There are about seventy of these overflows in the Genk treatment area. There were several problems. Firstly, the majority of these overflow structures were outdated or damaged, as a result of which they did not work optimally and flooded uncontrollably. Secondly, when the water level was high, the rainwater from the Stiemer flowed to the collector in different places instead of the other way around. As a result, clean Stiemer water ended up in the sewer system and then in our treatment plant, where the dirty water arrived too diluted to be purified. Finally, the overflows came into operation too quickly, sometimes causing wastewater to end up in the Stiemer.
The sewerage works took place at about 25 places at the collector. First of all, old overflow structures were demolished, existing ones were modified and new ones were built. Non-return valves were also placed on the overflow pipe so that the Stiemer can no longer flow back into the system. In addition, sewer covers were anchored to the collector along the Stiemer. For example, in the event of overpressure, the water cannot escape through the street covers, but is controlled via the overflows. Finally, extra emergency outlets were placed on the collector.
In order to avoid nuisance for the residents of the city of Genk, a study was also carried out as part of this project into the presence of basement connections and a possible risk of water flowing back to the houses. These residents were written to and were entitled to a small non-return valve at the level of their connection to the sewer system.
Additional work will be carried out later to keep the rainwater in the neighbourhoods where it infiltrates into the groundwater for as long as possible, and to drain clean water to a new, natural stream that will meander along the Stiemerbeek valley and further replenish the groundwater.
